a. An appliance to permit relative movement between the rope and rods in a
cable drill. It reduces shocks and the risk of rod or chisel breakages.
See also:free-falling device
b. To loosen or free stuck drill-stem equipment or tools by impacts
delivered by quick, sharp, upward-traveling blows delivered by a drive
hammer or jars. Long
A swell coupling, attached to the upper exposed end of a drill rod or
casing string, to act as an anvil against which the impact blows of a
drive hammer are delivered and transmitted to the rod or casing string;
also, sometimes used as a syn. for drive hammer. Also called drive collar;
jar head. Syn:bell jar
A colorless, yellow, or smoky gem variety of zircon.
A monoclinic mineral, NaSr3 Al3 (F,OH)16 ; in
brownish crystals and spherulites at Ivigtut, Greenland.
a. A small batch mill of ceramic material used in ore-testing laboratories
in investigation of grinding problems. Pryor, 3
b. Any of the stoneware-lined pebble mills used in milling enamels on a
small scale. Enam. Dict.
c. See:ball mill
This taper of 0.6 in/ft (4.2 cm/m) is used by a number of manufacturers
for taper pins, sockets, and shanks used on machine tools. Crispin
A trigonal mineral, KFe3 (SO4 )2 (OH)6 ;
alunite group; amber yellow to dark brown; forms druses of minute
crystals, crusts, and coatings; may be fibrous or fine-grained and
massive; associated with volcanic rocks; thought to form under solfataric
conditions at elevated temperatures and pressures; in some places with
alunite; at many localities in the Western United States, Bolivia, Europe,
and Russia. See also:cuprojarosite; kirovite.
See:agate jasper
A red variety of chalcedony. See also:chert; chalcedony.
Syn:jasperite
See:jaspilite
Banded jasper of varying colors.
See:jasper
The conversion or alteration of igneous or sedimentary rocks into banded
rocks like jaspilite by metasomatic introduction of iron oxides and
cryptocrystalline silica. See also:jaspilite
a. A dense, usually gray, chertlike siliceous rock, in which chalcedony or
cryptocrystalline quartz has replaced the carbonate minerals of limestone
or dolomite; a silicified limestone. It typically develops as the gangue
of metasomatic sulfide deposits of the lead-zinc type, such as those of
Missouri, Oklahoma, and Kansas. AGI
b. Resembling jasper. AGI
An almost opaque common opal; commonly yellow-brown, reddish brown to red
owing to iron oxides; resembles opal but has the luster of common opal.
Also called jaspopal.
Resembling or containing jasper; jaspery. AGI
Interbedded jasper and iron oxides. CF:iron formation
Syn:jasper bar
An opaque onyx, part or all of whose bands consist of jasper.
a. In a crusher, one of a pair of nearly flat or ribbed faces separated by
a wedge-shaped opening. Nichols, 1
b. One or a set of two or more serrate-faced members between which an
object may be grasped and held firmly, as in a vise, drill chuck, foot
clamp, or pipe wrench. Long
c. In a clutch, one of a pair of toothed rings, the teeth of which face
each other. Nichols, 1
See:jaw crusher
a. A primary crusher designed to reduce large rocks or ores to sizes
capable of being handled by any of the secondary crushers.
Enam. Dict.
b. A crushing machine consisting of a moving jaw, hinged at one end, which
swings toward and away from a stationary jaw in a regular oscillatory
cycle. ACSG, 2
c. A machine for reducing the size of materials by impact or crushing
between a fixed plate and an oscillating plate, or between two oscillating
plates, forming a tapered jaw. Syn:jaw breaker